What is the significance of a slightly elevated International Normalized Ratio (INR) of 1.97 in a patient taking Coumadin (warfarin)?

From the Guidelines

You should continue taking your current Coumadin dose but inform your healthcare provider about this result promptly, as an INR of 1.97 is slightly below the typical target range for most conditions, which is usually 2.0-3.0. This decision is based on the evidence from a study published in Chest 1, which suggests that warfarin doses do not need to be changed for INRs between 1.7 and 3.3. The study found that results were similar at follow-up 2 weeks later, with 44% outside the therapeutic range among patients randomized to a one-time dose change compared with 40% of those randomized to no dose change.

Key Considerations

• Do not adjust your dose without medical guidance, as this can lead to further complications.
• Your provider may recommend a small dose increase or more frequent monitoring until your INR reaches the target range.
• While an INR of 1.97 is very close to 2.0 and may be acceptable for some patients depending on their specific condition, it generally indicates slightly insufficient anticoagulation for most indications.
• This means you may have a slightly increased risk of clot formation compared to being in the target range.

Additional Recommendations

• Continue to be consistent with your diet, especially regarding vitamin K-containing foods like leafy greens, as these can affect your INR.
• Inform your provider about any new medications, supplements, or significant dietary changes, as these can interact with Coumadin.
• Remember that regular INR monitoring is essential for safe and effective Coumadin therapy, and it is reasonable to follow up with an INR after 1 to 2 weeks to exclude a progressive deviation from the therapeutic range, as suggested by the study in Chest 1.

From the FDA Drug Label

The PT should be determined daily after the administration of the initial dose until PT/INR results stabilize in the therapeutic range. Intervals between subsequent PT/INR determinations should be based upon the physician’s judgment of the patient’s reliability and response to warfarin sodium tablets in order to maintain the individual within the therapeutic range Acceptable intervals for PT/INR determinations are normally within the range of one to four weeks after a stable dosage has been determined

The patient's INR is 1.97, which is below the typical therapeutic range of 2.0-3.0 for most indications.

• The patient may require a dose adjustment to achieve a therapeutic INR.
• The decision to adjust the dose should be based on the patient's individual response to warfarin and their clinical condition.
• The physician should use their judgment to determine the best course of action, taking into account the patient's reliability, response to warfarin, and other factors that may affect the anticoagulant response 2.

From the Research

INR 1.97 while on Coumadin

• The patient's INR level is 1.97, which is below the therapeutic range of 2-3 for most patients on warfarin therapy 3.
• According to a study published in The American Journal of Medicine, adjusting a steady-state warfarin dose depends on the measured INR values and clinical factors, and the dose does not need to be adjusted for a single INR that is slightly out of range 3.
• The study suggests that most changes should alter the total weekly dose by 5% to 20%, and the INR should be monitored frequently, especially immediately after initiation of warfarin 3.
• Another study published in the Lancet found that low-dose oral vitamin K is more effective than placebo for the rapid lowering of raised INR values in patients taking warfarin, but this may not be relevant for an INR of 1.97, which is not considered elevated 4.
• A study published in Sisli Etfal Hastanesi tip bulteni found that 57% of patients on warfarin were not in the therapeutic range, and INR awareness was extremely low in the majority of patients 5.
• The study suggests that patients who knew the meaning of INR were more likely to have INR levels in the effective range, but these rates were not statistically significant 5.
• A study published in Seminars in Thrombosis and Hemostasis discussed the importance of accurate INR values for patient management, and the need for laboratories to verify their mean normal prothrombin time and international sensitivity index values 6.
• Another study published in Archives of Pathology & Laboratory Medicine found that the activity levels of vitamin K-dependent coagulation factors declined with increasing INR, but not at the same rate and not to the same level at a given INR 7.
• The study suggests that most of the values were below the hemostatic value once the INR was 3.6 or more, which is considered critical for physician notification 7.

Management of INR 1.97

• The patient's warfarin dose may need to be adjusted to achieve an INR within the therapeutic range of 2-3 3.
• The patient should be monitored frequently to ensure that their INR level is within the therapeutic range, and to minimize the risk of thrombotic or bleeding complications 3.
• The patient should be educated on the importance of INR monitoring, and the need to maintain a consistent diet and medication regimen to minimize fluctuations in INR levels 5.